Usage:
Introduction
This troubleshooting guide can be an aid for the service personnel to find the cause of existing problems. Several common problems are covered in the guide, but these problems are not arranged in any particular sequence.
Identify your particular type of problem from the Troubleshooting Index, then go directly to that problem in the guide. However, when you begin the procedure for that problem, start at Step 1 and follow through the step by step procedure. The steps that follow in a particular problem provide a definite sequence to be followed for a logical, one by one elimination of many variables. These steps are arranged in order from the more probable/easiest to check, to the less probable/more complex to check.
Whenever the cause of the problem is found and corrected, stop the test. Do not continue through the complete procedure just because it is there.
Governor Only
Problem No. 1: Governor Does Not Open On Starting
Probable Cause:
- 1. No signal from magnetic pickup. Verify with AC voltmeter or Oscilloscope.
Excessive pickup clearance. Adjust clearance to 0.5 to 0.8 mm (.02 to .03 in) if necessary.
Check resistance at cable socket of governor control unit A2/B2 (approx. 200 ohms). Replace cable or speed pickup if needed.
Check starting speed voltage at cable socket of governor control unit A2/B2 (approx. 5V AC). Replace or clean speed pickup if needed. The governor must have its own speed pickup. It cannot share a pickup with another device.
Wiring fault - magnetic pickup defective. Repair or replace as needed.
Control lamp must be lit when power supply is on and must go out from starting frequency upwards.
NOTE: If the governor works with the governor test unit but not on the engine, the fault is in the speed pickup or speed pickup cable.
- 2. Shutdown switch on.
Disconnect shutdown at pins H3 & I3 for troubleshooting.
- 3. Set point potentiometer connections wrong or incomplete.
Disconnect 14 pin connector from governor control unit and use ohmmeter to verify the resistance at the cable socket of the wiring harness.
Remote speed set point potentiometer at minimum speed:
Remote speed set point potentiometer at maximum speed:
- 4. Set point potentiometer or maximum speed/low speed potentiometer settings too low.
Verify speeds are correct with governor test unit.
- 5. Wiring fault in cable harness.
- 6. Supply voltage inadequate or polarity reversed.
Verify with DC voltmeter.
- 7. No DC voltage at governor control unit.
Verify with DC voltmeter.
- 8. Actuator impeded or linkage adjusted wrong.
Manually move linkage to verify.
- 9. Start fuel limit incorrectly adjusted (if used).
Put start fuel limit switch in position 2 or 3. Try to start engine. If engine starts, shut down engine, put start fuel limit slide switch in position 4. Re-adjust start fuel limit according to "Start Fuel Limit Adjustment" procedure in the Initial Checks & Adjustments section.
- 10. Open or shorted speed pickup cable or speed set point cable.
Verify with ohmmeter.
- 11. Actuator defective.
Check resistance at terminals B-C on actuator (approx. 2 ohms).
Replace actuator.
- 12. Governor control unit defective.
Replace governor control unit.
Problem No. 2: Governor Moves To Maximum Fuel Injection When Power Supply Is On
Probable Cause:
- 1. Wiring fault in harness.
- 2. Faults in magnetic pickup cable.
Check shield.
- 3. Terminals H3 and J3 of governor control unit connected defeating speed pickup failsafe (only on governor control units with a serial number of 90-0201499-30 or higher).
Remove connection between terminals H3 and J3. Terminals H3 and J3 should only be jumpered when setting start fuel limit or when troubleshooting governor control unit.
- 4. Governor control unit defective.
Replace and retest.
Problem No. 3: Engine Overspeeds On Starting
Probable Cause:
- 1. Maximum speed potentiometer setting too high.
Verify maximum speed with governor test unit.
- 2. Excessive magnetic pickup clearance (only a portion of gear-teeth recorded).
Verify gap is correct.
- 3. Poor contact in magnetic pickup line.
Check all connections.
- 4. Linkage cannot move freely.
Move linkage manually.
- 5. Feedback voltage incorrectly adjusted.
Verify with governor test unit or DC voltmeter.
- 6. Actuator or governor control unit defective.
Replace and retest.
If actuator applies torque in one direction only, the fault is the governor control unit.
Problem No. 4: Governor Unstable
Probable Cause:
- 1. Noise in magnetic pickup cable.
Check shield.
- 2. Noise in remote speed set point potentiometer cable.
Check shield.
- 3. Load fluctuations.
Run engine at constant load for troubleshooting.
- 4. Faults in speed set point signal (defective speed potentiometer or external speed setting device).
Verify this signal is steady with multimeter.
- 5. Supply voltage too low.
Verify voltage is 20 to 35V DC.
- 6. Poor electrical contact.
Check with ohmmeter.
- 7. Play or excessive friction in linkage.
Replace rod ends if worn.
- 8. Feedback voltage not properly adjusted.
Verify voltage is 1.5 to 5V DC.
- 9. Governor incorrectly adjusted.
Verify setup procedure was performed correctly.
- 10. Oil or metal shavings in tip of speed pickup.
Clean or replace speed pickup.
Problem No. 5: Reduced Speed Under Load
Probable Cause:
- 1. Droop-Isoch selector switch in droop position.
Switch to Isoch position if desired.
- 2. Actuator on 100% fuel injection stop;
Engine is overloaded.
- 3. Fault in governor control unit.
Replace governor control unit and retest.
Problem No. 6: Governor Linkage Is Hunting
Probable Cause:
- 1. Excessive voltage fluctuation of the supply voltage.
Verify constant DC supply.
- 2. Faults at the shields.
Check shield.
- 3. Poor set point signal.
Verify steady signal with multimeter. If remote speed set point potentiometer is used, connect governor test unit following procedure for Rated Speed and shake potentiometer while watching governor test unit readout. If readout changes while shaking, potentiometer is defective.
NOTE: If the actuator moves violently back and forth between shutoff and full fuel, this indicates the power supply voltage is unsteady or not of sufficient amperage (8A min) at the control. Use a voltmeter to verify steady DC voltage at the control. The maximum tolerable voltage fluctuation is 10%, and should be less. The DC voltage at the control should not drop more than 1V between the non-running engine and the engine at rated load. A large voltage drop could indicate too small diameter power cables, bad connections, or a power supply with inadequate amperage. Verify wire diameters are correct by referring to wiring schematic. Verify power supply meets requirements of Power Supply Check procedure in the Initial Checks & Adjustments section.
Problem No. 7: Engine Runs Smoothly At Most RPM'S, But Is Unstable Or Goes To Shutoff At A Certain RPM (when speed is adjusted with remote speed set point potentiometer)
Probable Cause:
- 1. Defective or corroded spot on remote speed set point potentiometer.
Do one or more of the following three tests:
(a) Check resistance of potentiometer over its entire range using resistance values found in "Problem No. 1, Step 3". If at some point the resistance changes drastically (not linearly), replace potentiometer.
(b) Connect Governor Test Unit according to "Procedure 2. Rated Speed" in Initial Checks & Adjustments section. Turn remote speed potentiometer slowly from minimum to maximum speed while watching display on Governor Test Unit. A sudden change in the frequency displayed on the Governor Test Unit indicates a bad spot on the potentiometer winding and the potentiometer must be replaced.
(c) Decrease the rated speed setting of the governor by about 5% following "Procedure 2. Rated Speed". Start engine with remote speed set point potentiometer set at minimum speed. Slowly increase speed of engine. If the engine is unstable or goes to shutoff at a certain rpm, but it is a slightly lower rpm than before, this indicates a bad spot on the potentiometer winding. Verify this is true by moving through the unstable point rapidly. Replace potentiometer if needed.
Problem No. 8: Generator Goes To Full Load Or No Load When Paralleled With The Utility Or Droop Bus (LMG 03 Loadshare Unit Not Used)
Probable Cause:
- 1. KG30 in isochronous mode.
KG30 must be set for droop mode. Verify the "Droop-Isoch" switch is in the droop (left-most) position and internal droop potentiometer of KG30 is not fully counterclockwise (CCW) against stop (zero droop position). See "Procedure 4. Droop Adjustment".
Governor With LMG 03 Loadshare Unit
Problem No. 9: Generator Set Does Not Share Load With Other Units Or Trips Out On Reverse Power
Probable Cause:
- 1. Incorrect connections on paralleling terminals 17 through 21.
See wiring schematic. Verify that load sharing lines 17 through 21 are correct.
- 2. Gain adjusted wrong.
Verify that gain was adjusted following LMG 03 Basic Setup Procedure, step 5.
- 3. Current transformers or potential transformers wired incorrectly.
Verify that LMG 03 Basic Setup Procedure, step 6, was performed correctly.
- 4. Speed setting wrong at no load.
Take the generator off the bus. Adjust speed of engine at no load to the exact rated rpm.
- 5. Load limit in effect while running in prime power (island) operation.
Load limit can only be used when paralleled to the utility. Turn load limit potentiometer fully clockwise (CW).
- 6. No AC power to the LMG 03 or one phase is missing.
With engine running at rated speed, use AC voltmeter to verify AC voltage across terminals 1 and 115V is 115V AC ± 15%, or across terminal 1 and 220V is 220V AC ± 15%, whichever supply voltage is used. Also verify potential transformer AC voltage across the terminals as follows:
- T2-T3 (320 to 440V AC phase-phase) or (185 to 255V AC phase-neutral)T3-T4 (320 to 440V AC phase-phase) or (185 to 255V AC phase-neutral)T2-T4 (320 to 440V AC phase-phase) or (185 to 255V AC phase-neutral)
Or
- T2A-T3A (170 to 230V AC phase-phase) or (100 to 130V AC phase-neutral)T3A-T4A (170 to 230V AC phase-phase) or (100 to 130V AC phase-neutral)T2A-T4A (170 to 230V AC phase-phase) or (100 to 130V AC phase-neutral)
Problem No. 10: Speed Of Generator Set Drops When Loaded When It Is Desired To Run Isochronous
Probable Cause:
- 1. Actuator against rack stop.
If the actuator is against the rack stop, engine is overloaded.
- 2. KG30 and/or LMG 03 set for droop operation.
The Droop-Isoch switch of the KG30 must be set to the Isoch (right-most) position, and the isochronous relay of the LMG 03 (terminals 23 & 24) must be closed by the paralleling relay (verify). If terminals 23 & 24 of the LMG 03 are not closed, the governor operates in droop.
- 3. Short circuit in paralleling lines.
Verify load sharing lines 17, 18, 20 and 21 are connected correctly and not shorted.
Problem No. 11: Engines Do Not Share Load Equally
Probable Cause:
- 1. Maximum load sharing not correct.
The GAIN Voltage is incorrectly adjusted. Verify LMG 03 Basic Setup Procedure, step 5 (adjusting the gain) was performed correctly. Apply a steady load to the generators. Check the gain voltage at TP10 (+) and TP11 (-) with voltmeter in 0 to 20V DC range. The gain voltage read at TP10 and TP11 must be the same for all of the LMG 03 units which are load sharing. If this voltage varies from unit to unit, readjust GAIN.
- 2. Minimum load sharing not correct.
No load speed of engine(s) set wrong. Verify KG30 control units are set to isochronous mode, then set each engine at precisely rated frequency at no load. This must be done with the generator taken off the bus.
Problem No. 12: Generator Does Not Take Load When In Parallel With The Utility
Probable Cause:
- 1. Load limit set too low.
Verify internal load limit of LMG 03 is set to desired point by following Procedure D. Utility Operation - Setting Of Internal Load Limit.
If external load limit potentiometer is used, verify that it is set correctly following Procedure E. Utility Operation - Remotely Set Maximum Load Limit.
- 2. Load setting is too low.
Verify load adjusting potentiometer is set to desired load level. See Procedure C. Utility Operation - Load Adjusting.
Verify load setting potentiometer is connected correctly to the LMG 03. Shut down engine. With power turned off to LMG 03, label and remove potentiometer leads from T13, T17 & T19. With ohmmeter, check resistance between terminals. The wiper of the potentiometer (terminal B) must be jumpered across the relay for this test. The resistance should read as follows:
- 3. Actuator linkage stuck or binding.
Check linkage for free movement over its entire range.
- 4. Power supply level in LMG 03 not normal.
Verify the following voltages with voltmeter in 0 to 20V DC range.
- T23 (-) & T11 (+) approximately -14V DCT23 (-) & T13 (+) approximately + 14V DC
The DC voltage measured does not have to be exactly + or -14V DC, but it should be the same for all of the LMG 03 Loadshare units. If voltages are not correct, verify AC input power supply at T1 and 115V or T1 and 220V is correct. If the AC supply voltage is correct, the problem could be internal in the LMG 03. Replace unit and retest to verify.
Problem No. 13: Generator Overloads When In Parallel With Utility
Probable Cause:
- 1. Both load limit and load setting of the LMG 03 are too high.
Verify Procedures C, D and E in the LMG 03 Loadshare Unit section were performed correctly.
- 2. Gain voltage not correctly adjusted.
Verify gain voltage was adjusted following LMG 03 Basic Setup Procedure in the LMG 03 Loadshare Unit section.
Problem No. 14: When a 5000 ohm Potentiometer Is Connected To LMG 03 And Is Used To Adjust Generator Load Or Load Limit, Load Can Be Adjusted Smoothly Over Most Of The Poteniometer's Range, But At A Certain Point The Load Increases Or Decreases Drastically (Possibly To Full Or No Load)
Probable Cause:
- 1. Defective or corroded spot on potentiometer winding.
Check resistance of potentiometer over its entire range using resistance values found in Problem No. 1, Step No. 3. If at some point the resistance changes drastically (not linearly), replace potentiometer.
Verify potentiometer is bad by turning potentiometer through bad spot rapidly while engine is running and generator is loaded.